Complexes of a macrocyclic polyether with one or more sulfur-bearing compounds

ABSTRACT

A complex of (A) an organic sulfur-bearing compound and (B) a macrocyclic polyether having a 15-60 carbon and oxygen ring and 1-4 fused carbocyclic rings; the ratio of A:B being about 1:1 to about 6:1. The complex can be used as a curing component for vulcanization of sulfur-curable elastomers.

United States Patent [191 Pedersen COMPLEXES OF A MACROCYCLIC POLYETHER WITH ONE OR MORE SULFUR-BEARING COMPOUNDS [75] lnventor: Charles John Pedersen, Salem, NJ,

[73] Assignee: E. l. du Pont de Nemours and Company, Wilmington, Del.

122] Filed: Nov. 27, 1970 Appl. No.: 93,424

152] U.S. Cl 260/340.3, 252/182, 260/795,

[51] Int. Cl C07d 19/00 [58] Field of Search 260/3403 [56] References Cited UNITED STATES PATENTS 3.546318 12/1970 Vest 260/3403 X Mar. 25, 1975 3,580,889 5/1971 Barney et al 260/3403 X FOREIGN PATENTS OR APPLICATIONS 1,455,518 11/1961 France 671,840 2/1939 Germany 260/3403 Primary E.\'aminerDonald G. Daus Assistant Examiner-James H. Turnipseed [57] ABSTRACT A complex of (A) an organic sulfur-bearing compound and (B) a macrocyclic polyether having a 15-60 carbon and oxygen ring and 1-4 fused curbocyclic rings; the ratio of AB being about 1:1 to about 6:1. The complex can be used as a curing component for vulcanization of sulfur-curable elastomers,

5 Claims, N0 Drawings COMPLEXES OF A MACROCYCLIC POLYETHER WITH ONE OR MORE SULFUR-BEARING COMPOUNDS BACKGROUND This invention relates to macrocyclic polyethers and complexes thereof. More specifically this invention relates to macrocyclic polyether complexes with organic sulfur-bearing compounds and the use of these complexes as components of a vulcanization system for sulfur-curable elastomers.

Vulcanizing sulfur-curable elastomers is a very complicated process requiring precise control of the vulcanization rate and ultimate cure for each application contemplated for the elastomer composition. Curing is affected by reaction of the numerous components in the elastomer recipe, their solubility in the elastomer, the heat generated in milling the compounds into the elastomer, the heat and time required to activate the various compounds for curing, and other factors. Thus, effective curing components which can be used to control vulcanization, which have good solubility in various elastomers and which provide easy processability are needed. The complexes of this invention meet such needs and provide a new versatility in vulcanization of sulfur-curable elastomers.

SUMMARY OF THE INVENTION Complexes of macrocyclic polyethers and cationic metallic compounds are known, but it has now been discovered that particular macrocyclic polyethers from complexes with neutral organic sulfur-bearing compounds. Certain of these new complexes function as vulcanization components. They produce a faster cure with higher modulus. tensile, and elongation for a given curing time when compared to the uncomplexed sulfurbearing compound. Thus, the complexes of this invention offer, not only greater versatility in compounding, but also more effective curing.

According to this invention there is provided a complex of (A) an organic sulfur-bearing compound, and (B) a macrocyclic polyether compound consisting of a macrocyclic ring of carbon and oxygen atoms totaling l5-60 ring atoms, the oxygen atoms in the ring being separated by links of two or three carbon atoms, said macrocyclic ring being fused to one to four carbocyclic rings from the groups (a) phenylene, naphthylene, phenanthrylene, and anthrylene; (b) hydrogenated analogs of (a); and (c) substituted derivatives of (a) and (b) wherein the substituents are halo, nitro, amino, azo, alkyl, aryl, aralkyl, alkoxy, cyano, hydroxy, carboxy, and sulfo. The ratio of sulfur-bearing compound (A) to the macrocyclic polyether (B) can range from about 1:1 to about 6:1.

Mixing the complex of this invention with sulfurcurable elastomer produces a composition which can be vulcanized by the application of heat.

DESCRIPTION OF THE INVENTION Macrocyclic polyethers which can be used to form the complexes of this invention are described in articles by C. J. Pederscn in the Journal of the American Chemical Society at 89; 7017 (1967) and 92:2; 39l (I970). The shorthand nomenclature for the polycthers set out in these articles will be used herein to refer to the macrocyclic polyethers generically as Crown compounds and the complexes formed therefrom as Crown Complexes.

Such crown compounds can be prepared by one of several chemical reaction methods. One method involves sequential reactions to build a particular crown compound by adding various links and reactive chemical groups as substantially linear chains attached to a starting group such as carbocyclic ring. ln this method the chains are cyclized to form the crown. Symmetrical crowns can be easily made by cyclizing starting group having one substantially linear chain with another such group. Methods of preparing crowns are described in French Pat. No. 1,440,716 and British Pat. No. 1,149,229.

In preparing crown compounds the sequence of chemical reactions and reaction conditions must be developed to produce the particular crown configuration desired. Reactions and reaction conditions to add the desired links and reactive groups are within the skill of the artisan and can be developed into a sequence to produce the desired crown with the information disclosed in the references cited above.

The precise method by which the crown complexes of this invention are formed, i.e. the chemical structure, is not fully understood. Complexes of the organic sulfur-bearing compounds and crown compounds of this invention can be formed by several methods. The exact chemical structure is not critical and can vary according to the particular crown, sulfur-bearing compound, ratio of crown and compound, and method of formation. Relative size, configuration, and presence of reactive groups of both crown and sulfur-bearing compound determine complexing ability and structure of a particular complex. Due to the nature of preferred sulfur-bearing compounds, crown compounds of less than 15 ring atoms do not readily form complexes with these compounds. Steric hindrance can also inhibit complex formation.

Crown compounds having a macrocyclic ring of 15-60 carbon atoms, and preferably more than 16 ring atoms, are of particular interest in preparing complexes of this invention. These crowns exhibit good complexing ability with a wide range of sulfur-bearing com pounds. A preferred group of crown compounds have 18 or more ring atoms; these compounds exhibit good complexing ability, as well as good activity asvulcanization components when complexed with sulfurbearing compounds. Crown compounds for this invention can also be classified by the number of oxygen atoms in the macrocyclic ring; a preferred group having five or more oxygen atoms exhibits good complexing ability with the sulfur-bearing compounds.

As used herein to describe the crown compounds of this invention, the term fused" refers to the structure by which a carbocyclic ring and the macrocyclic ring of the crown are attached. This term does not describe or limit the manner by which the crown is formed or by which other rings and substituents are attached to the crown. Fused rings of the crown compounds of this in' vention have two vicinial carbon atoms of the fused carbocyclic ring common to the macrocyclic ring of the crown. One or more carbocyclic rings and substituent groups can be attached to the crown in any compatible I stituents which can be attached to a carbocyclic ring include halo, nitro, amino, azo, alkyl, aryl. aralkyl. alkoxy. cyano. hydroxy, carboxy. and sulfo groups. Substituents which can be attached to a particular crown will be limited by the structure of the crown compound, the method or sequence of reactions used to form the crown, and compatibility of the crown and substituents with the intended complex and use.

The crown compounds comprise a series of carbon chain inks of 2 to 3 carbon atoms connected by oxygen atoms; thus. the basic crown compound is a cyclic polyether. At least one of the carbon atom links consist of the fused carbocyclic ring atoms discussed above. The other carbon link atoms can be either 2 or 3 carbon atoms with hydrogen atoms thereon (i.e. methylene groups) or carbon atoms with other compatible substituents. Both links of 3 and 3 carbon atoms can be present in a crown.

Organic sulfur-bearing compounds which are useful for forming complexes of this invention have utility as rubber chemicals. Such organic sulfurbearing compounds are referred to commonly and herein as sulfurbearing compounds. These sulfur-bearing compounds. such as thioureas and substituted thioureas, are vulcanizing agents for elastomers.

Chemically, sulfur-bearing compounds useful in forming the complexes of this invention can be described as aliphatic, aromatic, and hetcrocyclic hydrocarbon sulfur-bearing compounds. Such compounds come from the classes thioureas. thiobenzamides, and thiocarbazides. Substituted thioureas having one alkyl. aryl. or alkylene hydrocarbon substituent and substituted thioureas having two alkyl substituents on one nitrogen atom are included in the above class or thioureas. Substituted amides of aromatic thioacids having one alkyl substituent on the nitrogen atom are included in the above class of thiobenzamides. Substituted thiosemicarbazides having one aryl substituent on a nitro gen atom are included in the above class of thiosemicarbazides. Preferred alkyl substituents have from 1 to carbon atoms and preferred aryl substituents have from 6 to 22 carbon atoms. Other substituent groups which do not substantially interfere with complex formation or vulcanization using the complex can be present on the alkyl and aryl groups of the sulfurbearing compounds.

Examples and the structure of compounds within the above sulfur-bearing compound classes include:

thiobenzamides:

l. thiobenzamide a -C-NH C thiosemicarbazides:

l. thiosemicarbazide:

N ll-N 2. l-phenylthiosemicarbazide 3 l-phe nylthiosemicarbaz ide Other compounds and substituted compounds from these groups can be used which complex with crown compounds of this invention. Preferred compounds include thiourea. Z-mercaptoimidazoline, thiobenzamide. thiosemicarbazide. N-phenylthiourea, and 4-phenylthiosemicarbazide because these compounds most readily form complexes.

There are several methods for preparing the complexes of this invention. In a preferred method the sulfur-bearing compound and crown compound are precipitated in the desired ratios from a saturated solution by a slight decrease in temperature. The ratio of the crown compound to the sulfur-bearing compound as precipitated in the complex depends upon the ability of the compounds to complex, the solubility of each and the ratio of the two compounds before precipitation. Any solvent which will dissolve the compounds and does not react or prevent complex formation is suitable, such as methanol. The ratio of the two or more compounds can be varied by varying the complex for mation conditions pointed out above. Complexes having a molar ratio of sulfur-bearing compound to crown compound in the range of about 1:] to about 6:] can be readily formed by the above method.

Other methods of forming complexes of this invention include:

I Crown compound and sulfur-bearing compound or compounds are dissolved in a solvent which dissolves each and the solvent is removed by evaporation. usually under vacuum. leaving the complex.

2. Crown compound is heated with sulfur-bearing compound in a solvent in which only the latter is readily soluble, the crown compound being com erted into complex without the system ever becoming a clear solution. The complex is recovered by filtration.

3. Crown compound is warmed and thoroughly mixed with the sulfur-bearing compound forming a complex by blending the dry compounds without a solvent.

The crown complexes of this invention are useful components for vulcanizing sulfur-curable elastomers. The precise nature of the chemical reaction by which these complexes function is not fully understood. Changes associated with vulcanization are complex and have not yet been completely chemically defined. Due to the great variety of compounds employed in sulfur-vulcanization and in overlapping functions of the sulfur and sulfur-bearing compounds, the role of each component is difficult to determine. However, it is evident that the complexes of this invention serve to improve the rate of cure, modulus, compression set, and other vulcanizate properties. This improvement is shown by comparing identically prepared portions of a sulfur-curable elastomer. A complexed sulfur-bearing compound of this invention is used in one portion. ldentical sulfur-bearing compound in uncomplexed form is used in the other portion. Higher cure rate, higher modulus, and lower compression set are illustrated by Examples 1 1 and 12 for two crown complexes in polychloroprene and styrene/1,3-butadiene rubbers.

Sulfur'curable elastomers which can be used with the crown complexes of this invention are generally elastomeric polymers having ethylenic unsaturation which can be cross-linked under vulcanization conditions by sulfur and sulfur-bearing compounds. Such sulfurcurable elastomers are known in the art. For purposes of this invention the sulfur-curable elastomers must have a minimum level of ethylenic unsaturation for a practical vulcanization rate and extent of vulcanization. This minimum level is about 0.1 gm. mole of ethylenic unsaturation per kilogram of elastomer. This value is commonly expressed as C C/Kg of elastomer and is calculated based on one of several methods for standard unsaturation determination. Methods for determining ethylenic unsaturation are described in US. Pat. No. 3,063,933 to Gladding et al. (using iodine absorption) and US. Pat. No. 3,365,418 to Nyce et a1. (using bromine absorption). For a good vulcanization rate preferred sulfur-curable elastomers have unsaturation levels on the order of at least 0.5 (C C)/Kg of elastomer.

Sulfur-curable elastomers which can be used with the crown complexes of this invention include styrene/- butadiene, polymers, ethy1ene/(C C )aolefin/(C -cn) non-conjugated diene polymers, polybutadiene. butyl rubber, acrylonitrile rubber, polyisoprene. natural rubber, unsaturated polyurethane, and polychloroprene. Such elastomers are described in the Kirk-Othmer Encyclopedia of Chemical Technology, 2nd edition. lnterscience Publishers, New York, under elastomers" and rubber" and in the Encyclopedia of Polymer Science and Technology, 1964 lnterscience Publishers, New York. Preferred elastomers from this group are the ethylene/(C CQa-olefin/(C Cn) nonconjugated diene polymers, styrene/butadiene polymcrs, and polychloroprene. The ethylene/(C CQaolefin/(C Clw) non-conjugated diene polymers are from a class of polymers commonly noted as EPDM elastomers and illustrated by an ethylene/- propylene/1,4-hexadiene elastomer. EPDM is defined at pages 678-679 of Part 28 of the 1966 Book of ASTM Standards (April 1966). Such elastomers are described in US. Pat. No. 3,278,480 to Radcliff. Styrene/butadiene polymers are illustrated by styrene/1,3-

butadiene copolymers commonly known as the 58K rubbers and illustrated by SBR-1500 which contains about 23.5 percent styrene and is made by co1d"polymerization (6C.). Polychloroprene is not normally considered a sulfur-curable rubber, but it can be used with the complexes of this invention and is illustrated by an elastomer marketed as Neoprene. Polyurethanes are described in United States Pat. No. 2,808,391 to Pattison. Other elastomers which are not commonly classed as sulfur-curable can be used with the complexes of this invention if sufficient unsaturation is introduced into the elastomer either by chemical means or by polymerizing a minor proportion of a monomer which would introduce unsaturation, such as a diene.

For vulcanization using the complexes of this invention other compatible agents can be used, such as particulate fillers, modifiers, extenders, curing agents. antioxidants, etc. Due to the extensive list and combination of such compounds, compatibility and proportions for each agent in the compounding recipe must be de termined for each combination. This determination is within the skill of the artisan with minimum experimentation.

Mixing and vulcanizing the complexes of this invention with elastomer can be accomplished by one of several conventional, well-known methods. Mixing can be accomplished by dispersing the complex in elastomer in latex form or by compounding. Compounding in volves mechanically blending materials of the recipe in a conventional sequence. A roll-mill, Banbury mill. or other conventional machinery can be used for blending the materials. Compounded elastomer can be formed, molded, extruded, or otherwise shaped as desired. It can be cured with the application of heat or heat and pressure to the desired state of cure as determined by the particular vulcanizate properties desired according to well-known methods.

The following examples illustrate. the invention. Parts, percentages, ratios, and concentrations are by weight unless otherwise indicated, except for ratios of compounds in complexes which are molar ratios.

EXAMPLE 1 Preparation of (Dibenzo-lS-crown-S). Thiourea (1:1 molar) Analysis yields the following data:

Found for Product Culcd for (C ll- .0,)

. ((HJQ SI Melting 1 l4 l 15C.

Point Melting points for: crown ilscll', l(16-l07"(.; thiourea. llll)--1X2"(.

EXAMPLE 2 Preparation of(Benzo-l-crown-5) '4 (Thiourea) (1:4 molar) A 3-gram (0.0112 mols) portion of 2.3-benzo- 1,4,7, 1 0,1 3-pentaoxacyclopentadeca-Z-ene (Benzol5-crown-5) is added to 50 milliliters of a methanol solution containing 4.85 grams (0.065 moi) of thiourea. The resulting mixture is heated on a steam bath until all solids have dissolved. filtered hot. and allowed to cool. The white crystals which separate are washed with methanol and dried.

Analysis yields the following:

Melting points for crown itself. 6R 5-69 5C.. thiourca 180-1821 The 1:5 complexes with thiourea of cis, trans isomers of dicyclohexyl-l8-crown-6 melt as follows:

complex mp.

Found for Product Calcd for (CHH-NOSJ 4 ls isomer m.p. til-62C. l72-l7x"(v H N2S] trans isomer m.O. 69-70C.) l97-20()(' 71C 38.1 37.7 71H: 6 2 6,1 /1l\l2 19.6 19 6 '45; 221i 224 2() EXAMPLE 5 Melting l52-Io4(.

P )i it l l A. Preparation of 2,3-Benzol 1,12-tetramethylcne- Melting l |l\l l'or &.r\\\\fl ILscll'. 7'7-'l)(' thlourcn. 180- 182C l,4,7, l l 3, l (T-l'leXilUXZlCyClOUClZldCCU-ZCHC EXAMPLE 3 Preparation of (Bisbutylbenzo-l8-crown-6) 6 Thiourea (1:6 molar) Substitution of 2,3,11,l2bis(tertbutyl benzo)- 1 ,4,7.10.l 3, l6-hexaoxacyclooctadeca-2, l l-diene (Bisbutylbenzo-l8-crown-6) in place of 2,3-ben2ol,4,7,l0,13'pentaoxacyclopentadeca-Z-ene in the procedure of Example 2 gives white crystals of the 1:6 molar complex.

Analysis yields the following data:

Found for Product Calcd for (C ,.H O 6 ICH N S) 71C: 52.9. 43.l 44.0 /(HI 6.) 7.0 6.9 /IN: I61, I63 lX.| /S. 20 3. 20.5 20.7 Melting 17X 180C Point Melting points for cronn itself. l12-l34f thlourca. Hill-182C EXAMPLE 4 Preparation oflDicyclohexyll 8-crown-6) 6 Thiourea l :6 molar) failed for (CZUHIHKOG) 6 (CH,N SJ

Found for Product 71C: 371, 37.3 37.7 /rH: 6 7, 6.8 7.2 71N: 20.4. 20.6 20.3

(Benzo-cyclohexyl l 8-crown-6) A one-liter stainless steel autoclave is charged with 150 grams of 2,3,1l.l2-dibenzo-l,4.7,l0.l3,16- hexaoxacyclooctadeca-2,l ldiene (Dibenzol 8- crown-6), 28 grams of sodium chloride (in ml. wa ter), 250 m1. methanol, and 20 grams of catalyst (5 percent Ru on A1 0 Hydrogenation at C. and 500 psig is continued until 2.4 gram-mols of hydrogen have been taken up. The autoclave is cooled. hydrogen is vented, and the contents are removed and filtered. Concentration under vacuum gives a residue which is then extracted with 300 ml. of hot n-hexane; concentration of the soluble fraction (A) under vacuum gives a viscous liquid (fraction A) and some unreactcd crown. The hexane-insoluble fraction is dissolved in 300 ml hot benzene; the decanted solution is concen trated under vacuum to a white sticky solid. This residue is washed with 500 ml. methanol and filtered free of white crystals; the filtrate is concentrated and the concentrate extracted with hot hexane. The hexaneinsoluble fraction (B) and fraction A are combined to give fraction C. C is chromatographed on a 4 /4 in.l.D. x 9 /2 in. column of acid-washed A1 0 The first two 70-ml. n-hexane eluates are discarded; the next four 70 ml. eluates are concentrated to give a colorless viscous liquid (the desired product) having a number-average molecular weight (boiling point elevation) of 386: it analyzes 65.4 percent C. and 8.8 percent H by weight. B. Preparation of (Benzo-cyclohexyl-l8-crown6) Thiourea (1:6 and 1:5 molar) An 0.815 gram (0.00223 mol) portion of 2,3-henzol l,l2-tetramethylene1,4.7.10.13.l6-hexaoxacyclooc tadeca-Z-ene prepared by the procedure of Part A above is mixed at room temperature with 15 ml. of methanol saturated with thiourea 1.45 grams of thiourea; 0.0195 mol). Crystals separate. After 30 minutes the crystals are filtered away, washed with methanol, and dried yielding the 1:6 molar complex.

Analysis yields the following data:

-Continued Found for Product Calc'd for C2.,H;,.,O" Found for Product Calcd for (C .,H O ;l 2

(CH4NZS) (CTHN %H: 7.6 7.7 71C. 37.8. 38.0 37.9 an: 6.4. as 6.6 5 1N: 20.3 20.5 20.4 Melting 4s. 23.7. 23.9 23.4 P t Melting 17s 183C.

Polm *Melting points for crown itself. 68.5-69.5C; N-phenylthiourea. 154C.

The filtrate from which the 1:6 complex is isolated X M LES 3 9 deposits a second crop of white crystals, the 1:5 com- Preparation of (Dicyclohex l 18 p y l Analysis yields the following Values. (l-zb-th1osem1carba21de) or 2(4--th1osem1carbaz1de) (ltn molar) A mixture of 3.72 grams (0.098 mo1)of2,5,8,l5,l8,- Fmmd Product fgh ffgf 5 2l-hexaoxatricyclo [20.4.0.9 hexacosane 4 2 (Dicyclohexyl-l8-crown-6) and 1.67 grams of 1 (or 4-) 2 2 2 2% phenyl thiosemicarbazide (n 1 and 2 molar respeci 1 20 tively) is warmed in ml. of methanol until a solution (1s. I 21.6. 21.7 21.5 is obtained. On cooling, large white crystals of the com- {$122.8 plex (lzn) settle out. Analysis yields the data given below for the respective complexes:

25 EXAMPLE 6 Eour81d for Prague; Calc'd for X. X. Preparation of Benzo-lS-crown-S) 2 Thiobenzamide b) a- W GM (Cd- 11 251 A 1.253-gram (0.00915 mol) portion of thiobenza- (N= 1) (n 2) n =1 n 2 mide is mixed with 1.23 grams (0.0046 mol) of 2,3- 603 579 601 578 benzo- 1 .4,7. 10,13-pentaoxacyclopentadeca-2-ene in 751-1} 314 718 11,4 7:6 10 ml. of methanol. The resulting yellow solution is alif lowed to evaporate at 25C. The solid yellow residue 165C obtained is triturated with 5 ml. of cold methanol, filtered. washed with 5 ml. of cold methanol, and dried. ggf jgqgsgnm m *i1{;,.f" The 1:2 molar complex is obtained as bright yellow crystals.

Analysis yields the following data: EXAMPLE 10 40 Preparation of (Dicyclohexyl-l8-crown-6) 2 Found for Product Calc'd for (CHHNOS) (Z'mercaptolmldazolme) 1:2 molar) I 2(CH7NS) The general procedure of Examples 89 is followed but M4 620 using 1.02 grams (0.0086 mol) ofthe crown compound 3 5 and subst1tut1ng 3.72 grams (0.01 mol) of 2- 3% mercaptoimidazoline for l or 4 tb-thiosemicarbazide. Melting x1 a 82C. Hard white crystals of the 1:2 molar complex are ob- Point tained. "Melting pulllb for crown itself. 77-78C.; thiohenzamide. l 15-1 16C. Analysls ylelds the fonowlng values:

F0 nd for Product Calc'd fir (C1.,H;,O1;) 2 EXAMPLE 7 u (LCHHGIQZS) Preparation of (Dicyclohexyl-l8-crown-6) 7 2(N-d -thiourea) (1:2 molar) H A mixture of 1.52 grams (0.01 mol) of N- i; 3 :8 phenylthiourea and 3.8 grams (0.01 mol) of 2.5.8.151 Melting 125-127C 8.2 1 -hexaoxatricyclo [20.4.0.0-] hexacosane r|)iCyclOhexyl-|g'crOWn-fn In f metha'nQI Melting point for cruun itself. 68.5-69.5C'. 2-mercuptoimiduyolinc. ahmu warmed on a steam bath. The cop1ous wh1te prec1p1tate MT which appears is separated after the mixture has been cooled. The crystals are washed with methanol and EXAMPLE H dried.

Analysis yields the following data: y p

Polychloroprene 1s prepared by persulfatc catalyzed mercaptan-modified emulsion polymerization of 2- Fou d r Product cfllv'd g f ign v 3 chlorol .3-butadiene at 40C. It has a Mooney iscosity T t (ML 1+2.5 at C.) of about 50. "4C 611.0 60.3 B. Use of (Dicyclohexyl-l8-crown6) complexes Three stocks A-C containing the polychloroprene are compounded on a rubber roll mill according to the recipes given in the table below. Stocks A and B correspond to the invention. Stock C is a control outside the invention provided merely for purpose of comparison, thiourea is present. without the crown.

Component Parts by Weight Polychloroprene I Stearic acid 0.5 MgO (Maglite D") 4 N-phenyl-a-naphthylamine 2 Medium thermal black I00 Aromatic Petroleum Oil 12 (Sundex 790) ZnO Curing additive (prepared) (see table belovt asin Ex.4&7)

Stocks A-C are cured for minutes at l52.8C. (307F.).

EXAMPLE 12 Curing SBR A. Styrene/1.3-Butadiene Copolymer Rubber [SBR- I500] This sulfur-curable elastomer (SBR-1500). made by copolymerizing l.3-butadiene and styrene. contains about 23.5 percent by weight. lts Mooney Viscosity (ML l+4/l00C.) is about -52. The designation )0 pounded on a rubber roll mill according to the recipes STOCKS Additive A B C Type CP CT Thioureu Amount (phr) 0.93 069* 0,39

ODR (inehlhs);**** at 0 min. cure time 2 2 2 5 min. cure time 7 2 2 l0 min. cure time 37 8 5 20 min. cure time 53 23 I3 A ODR Torque/ A tlmax .2 l5 0.85

Vulcaniwte Properties:***** Modulus at ION/1 Ext. 400 300 250 (psi) Modulus at 200: Ext. 50 00 550 (psi) Tensile Strength (psi) I775 I550 I050 Extension at break ('1) 3|. 360 32.

Permanent Set at Break 1 4.5 7 r Compression Set l l) I2 29 so (22 hrs. at C.)

control,

*(Dicyclohexyl-l8-crown-6) 2(Phenylthiourea) (Pre ared as in Example 7) "(Dicyclohcxyl-l8-crown-6) 6(Thiourea) (Prepare as in Example 4) ***Contains 0.39 gram of complexed thiourea ****ODR (oscillating disc rheometer) results indicate rate of cure of compounded stock for tests using a commercial ODR such as a Monsanto Oscillating Disc Rheometer described in an Operation and Service Manual of the Monsanto Chemical Compan St. Louis. Missouri. The test procedure is described in an article by G. E. Decker. R. W. Wise, and D. Guerry in Rubber Chemistry and Technology." 36 pp. 451-458 1963) and in US. Pat. 3.523927 to Shaw. Briefly. ODR measures relative viscosity of an elastomer by oscillating a groo\ed biconical disc through an arc while pressed tightly between two test pieces. Torque required to oscillate the disc is recorded as the viscosity and curing is indicated by a rise in viscosity.

*****Vulcanizate Properties are determined by the following ASTM methods;

Mooney Viscosity ASTM Dl64(i-67 Modulus Tensile Strength Extension at Break Compression Set Permanent Set at Break ASTM D-4 l 2-66 modified by use of a 5 minute hold time).

ASTM 05495-67 (Method B) ASTM D4l266 (Section 5.5

13 given in the table below. Stocks A and B correspond to the invention. Stock C is a control for Stock B and is outside the invention. thiourea is present, but the crown is absent.

2 (min dddllD/C lPrepured (see table below) Stocks A-C are cured for 20 minutes at 150C.

1 claim:

1. A complex of (A) a thiourea and (B) a macrocyclic polyether having a macrocyclic ring of carbon and oxygen atoms totaling 15-60 ring atoms, each oxygen in the ring being separated from its adjoining oxygens in the ring by 2 or 3 carbon atoms, and the macrocyclic ring being fused by a pair of vicinal carbon atoms to 1-4 carbocyclic rings of the group: (a) phenylene, naphthylene, phenanthrylene, and anthrylene, (b) saturated analogs of (a), and (c) monosubstituted derivatives of (a) wherein the substituent is tertiary butyl.

2. A complex of claim 1 wherein the molar ratio of AB is about 1:1 to about 6:1.

3. A complex of claim 1 wherein the macrocyclic polyether has at least 5 oxygen atoms in the macrocyclic ring and the links consist of 2 carbon atoms.

4. A complex of claim 1 wherein the sulfur-bearing STOCKS A B C Additive 1 pe' CP C'T,,* Thiourca Amount t ihrl 8.9*** 3.6*** 2 ()DR line i-ohs):

.it min. cure tlme 0 7 5 min. cure time 16 9 6 11) min. eure time 32 15 7 11) min cure time 46 33 9 1) min. cure time 53 5O 12 t A ()DR lorque/ A Umax. 3.9 1.9 0.26 YuleunI/aite Properties at C J Modulus at 1011"; Ext. (psi) 301) 200 70 Modulus at 101M Ext. (psi) 77.5 400 75 lensile Siren th (psll 2675 I860 120 Extension tli reak 1'4] 441) 550 (JlO Permanent Set in Break (9? 2U 192 ('ompression Set 1'4 1 47 72 89 113 hr\. .11 7(|(' I control init tlohmyl 1K eru (1) 2 (Phenylthiourea)(Prepared as in Example 7) (Dit elohenl [Keronn-hl h (Thiouren) (Prepared as in Example 4] \;\I|\l.|1|\- I grams n1 eoniplewd thiouren Vulcanizate Properties are determined according to ASTM methods as set out in Example 11. 

1. A COMPLEX OF (A) A THIOUREA AND (B) A MACROCYCLIC POLYETHER HAVING A MACROCYCLIC RING OF CARBON AND OXYGEN ATOMS TOTALING 15-60 RING ATOMS, EACH OXYGEN IN THE RING BEING SEPARATED FROM ITS ADJOINING OXYGENS IN THE RING BY 2 OR 3 CARBON ATOMS, AND THE MACROCYCLIC RING OF THE GROUP; OF VICINAL CARBON ATOMS TO 1-4 CARBOCYCLIC RINGS OF THE GROUP: (A) PHENYLENE, NAPTHYLENE, PHENATHRYLENE, AND ANTHRYLENE, (B) SATURATED ANALOGS OF (A), AND (C) MONOSUBSTITUUTED DERIVATIVES OF (A) WHEREIN THE SUBSTITUENT IS TERTIARY BUTYL.
 2. A complex of claim 1 wherein the molar ratio of A:B is about 1:1 to about 6:1.
 3. A complex of claim 1 wherein the macrocyclic polyether has at least 5 oxygen atoms in the macrocyclic ring and the links consist of 2 carbon atoms.
 4. A complex of claim 1 wherein the sulfur-bearing compound is N-phenylthiourea.
 5. (Dicyclohexyl-18-crown-6).2(N-phenylthiourea). 